I've read about converting my MCI 9 oil filled hubs over to greased bearings, but I'm not 100% sure what's involved. Can I drain them, and splooge a ton of grease in them and slap the hub covers back on? Or does it require a bearing removal and repack? If so, I'm assuming that's drama?

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None of the trucks we sell have grease bearings anymore. Why would you want to switch? Oiled bearings are by far better then greased. Replace the hub seals, tighten the bearings properly, put new oil in and you're done! I changed my greased bearings to oil in 1993 and they haven't leaked yet. Good Luck, TomC

I would stick with the oil the rear axle needs a special seal to separate the oil from the grease buy some new Stemco covers and be done they last for years without problems yours are probably original

You're going to have to pull the hub off, pull off the seal, wash the inner bearing and pack it with grease, re-install a new grease type seal (might be the same as the oil type seal, but you need to check), then wash and pack the outer bearing with grease, reinstall the hub, set up the bearings with the correct clearance, then install a hub cap. I'm not sure if you can use the original oil type Stemco, or if you need to get a solid cap. When the hub is off you need to inspect the spacer at the base of the stub axle carefully to make sure it is still smooth enough to let the seal ride on it. Mine were very corroded so I spent a lot of time and effort polishing them smooth enough to let me install a speedy sleeve repair sleeve over the seal area. Is it a drama? I changed the seals on my hubs last year, it qualified as drama to me because it didn't go very smoothly. All of the drum fixing screws were rusted in place, I drilled them out and re-tapped the holes in the hubs. As mentioned the spacers were corroded and I had to put speedy sleeve repair kits on, which was a total and complete PITA (not enough room to use their install tool and the flange you have to peel off wouldn't peel off, so it was invent and bodge time at the Evans Bus Garage... The drums and hubs are heavy enough that you need to be very careful with them, and maybe even create a lift table to remove and install them. All in all it took me about three full days to do. It's not hard as in you need tremendous skill and experience to do the job, it's hard as in it's physically hard work. Mind you the work needed to change the seals and keep the oil filled hub system is about identical to the work required to change to grease.

I would personally keep the oil filled hubs. Oil is a better lubricant than grease, and if you have decent seals and hub caps and use Lucas hub oil you shouldn't have any leaks, just check them once in a while. It took some doing but I found new Stemco windows and sealing plugs for my hub caps so now I can even see the oil level from outside...

Learn something new everyday. I replaced my hub covers, so they don't leak a drop anymore. The front hub oil looks great, but I have change out the rear tag oil and it's already milky. I'll change it again and see what happens. Not sure why it's getting milky so fast. One last question, (and Brian, that is definitely drama in my opinion haha) how are the drive axles lubed? Oil also? Do I remove the little square plug to fill?

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Most times, what people assume is a leaking hub cap is a hub overfull condition which pushes it out the tiny vent hole in the rubber plug. There is a correct oil fill line on the hub cap but a lot of people fill them right up to the plug; guaranteed to leak then. You will have less maintenance with oil hubs, as long as the seal is installed correctly. On the GM's the maintenance manual says repack the bearings every 20,000 miles. That would get old. Slap a new Stemco hub cap on and add oil. I prefer Powerpunch. When folks paint over the clear plastic hub cap like on yours it kinda defeats the purpose of a quick glance to check hub oil level.

Scott, yes the drive hubs recieve oil from the differential. The plug is to fill the hubs when they are installed dry after a bearing change, etc. They will automatically fill to the correct oil level as long as the diff has the correct oil level, which is fill right to the fill plug on the diff housing.

I believe you have it covered, And that particular style rear housing is using in the same oil supply I agree.That drain and fill plug on the axle picture can be very handy in draining before removal "less mess" its a pain cleaning wheels. Using them to fill would be a study out of my league, my experience says that plug option was on the luxury list so having it in correct position to fill is probably in a book, and after this I will try and look a bit. I am more interested in helping find the color or problem with gear oil, what may be air bubbles from expansion or exactly im curious to help fix that. The tubes or axle vents are high and a buss in water that hi I want to see pics. Sorry! Im around rivers and some unfortunate times floods, and with an Army past with river operations as a mos lots of vehicles unloading in water was the task just here to help.Have a Good Day

Interesting. As for the overfill, mine bled out some fluid when I first drained and refilled after replacing the covers. Eventually they level out and it doesn't leak a drop. Again, I just need to repeat the drain and fill procedure in the tags cause the oil isn't staying clear.It's getting milky almost as if a small amount of water is getting in there. Might be time for some new plugs. I agree on the paint over the caps. I have to pull the plug to see the level. Annoying. Thank you so much. You guys are forever helpful.

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When I purchased my MC7, it had the grease type bearings, front and drive had the seals and tag was also grease type. That ended as soon as it was discovered, cleaned up, installed seal wear rings, seals correct bearing preload adjustment and used the hub oil on steering & tag, never any issues nor leaks.

Those part numbers are Stemco part numbers, they make the hub cap, the transparent plastic window and the rubber plug. The hub cap is an MCI specific part, not an industry standard part common to trucks but the window is one of their standard windows at 2.75" diameter and the rubber plug is just their normal rubber plug. I will take a picture of my hub caps so you can see what they look like, they look different to yours but yours are all painted over so it's hard to tell. I am pretty sure your 9 would have been the same as my 5C when it came from the factory, the other part numbers were for later model MCI's and Prevosts.